Mike Mayock and Sir Mix-A-Lot have something in common, sort of. They both like a nice, juicy caboose. The main difference is that offensive linemen, not groupies, need a big butt to roll in Mayock's Mercedes.
What the hell are we talking about? Mayock's explanation of North Carolina guard Jonathan Cooper, considered to be one of the top two interior linemen available in the 2013 NFL Draft, included high praise for the man's tight end.
And he really does have a point as to why that butt, and Cooper's ability to back it up, matters. But this also needs to be said.

The NFL Scouting Combine makes for some uncomfortable moments, with large men in tight outfits running with slow motion cameras clicking away.
One example of this pure awkwardness is the constant excitement of grown men when they see an offensive or defensive linemen with a large backside. Mike Mayock is on NFL Network, and he highlighted this point Saturday morning by exalting "See that big butt?"

Every general manager and scout wants to see a large rear end for a few reasons, the main one being power. A big butt says that the lineman has good lower body strength that can really help with push in the trenches.
Another reason is explosion off the line of scrimmage. While upper body strength is terrific, all the leverage a lineman needs is created from the waist down.